Liquid crystal display device

ABSTRACT

According to one embodiment, a liquid crystal display device includes a first substrate includes a first pixel electrode which comprises a first contact portion and a first strip electrode with a first length, a second pixel electrode which comprises a second contact portion located on a same straight line with the first contact portion and a second strip electrode with a second length equal to the first length, and a third pixel electrode which comprises a third contact portion disposed at a position displaced from the same straight line of the first contact portion and a third strip electrode with a third length different from the first length, a second substrate, and a liquid crystal layer held between the first substrate and the second substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2014-111502, filed May 29, 2014, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

Recently, a liquid crystal display device using a lateral electric field(including a fringing field) such as an in-plane switching (IPS) modehas been put into practical use. Such a liquid crystal display device ofthe lateral electric field mode comprises a pixel electrode and a commonelectrode formed on one of substrates.

In the liquid crystal display device of the lateral electric field mode,technology of uniforming properties of pixels of respective colors hasbeen known. The pixels of respective colors have pixel areas differentin color. The area ratios of the pixel electrodes to respective pixelareas are different from each other.

In addition, technology of reducing the lowering of the resolutionwithout increasing the number of wiring lines has been known. Thedisplay device has white sub-pixels besides red, green and bluesub-pixels. The area of each of the red and blue sub-pixels isapproximately twice as large as the area of each of the green and whitesub-pixels. The number of each of the green and white sub-pixels istwice as great as the number of each of the red and blue sub-pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing a configuration and an equivalentcircuit, of a liquid crystal display panel LPN which constitutes adisplay device of embodiments.

FIG. 2 is a schematic plan view showing a first configuration example ofpixels in an array substrate AR shown in FIG. 1 as seen from acounter-substrate side.

FIG. 3 is a plan view schematically showing a structure example ofswitching elements SW2 and SW3 shown in FIG. 2.

FIG. 4 is a plan view schematically showing an example of a layout ofeach pixel and color filters in the embodiments.

FIG. 5 is a cross-sectional view schematically showing a configurationof a liquid crystal display panel LPN including pixels PX1 to PX6 shownin FIG. 2.

FIG. 6 is a schematic plan view showing a second configuration exampleof the pixels in the array substrate AR shown in FIG. 1 as seen from thecounter-substrate side.

FIG. 7 is a schematic plan view showing a third configuration example ofthe pixels in the array substrate AR shown in FIG. 1 as seen from thecounter-substrate side.

DETAILED DESCRIPTION

In general, according to one embodiment, a liquid crystal display deviceincludes: a first substrate comprising first to third switchingelements, a first pixel electrode which comprises a first contactportion electrically connected with the first switching element and afirst strip electrode extended from the first contact portion with afirst length, a second pixel electrode which comprises a second contactportion electrically connected with the second switching element andlocated on a same straight line with the first contact portion and asecond strip electrode extended from the second contact portion with asecond length equal to the first length, and a third pixel electrodewhich comprises a third contact portion electrically connected with thethird switching element and disposed at a position displaced from thesame straight line of the first contact portion and a third stripelectrode extended from the third contact portion with a third lengthdifferent from the first length; a second substrate comprising a firstcolor filter opposed to the first pixel electrode, a second color filteropposed to the second pixel electrode, and a third color filter opposedto the third pixel electrode; and a liquid crystal layer held betweenthe first substrate and the second substrate.

The embodiments will be hereinafter described with reference to theaccompanying drawings. In the drawings, constituent elements having likeor similar functions are denoted by the same reference numbers orsymbols and their duplicated explanation is omitted.

FIG. 1 is a view schematically showing a configuration and an equivalentcircuit, of a liquid crystal display panel LPN which constitutes aliquid crystal display device of the embodiments.

More specifically, the liquid crystal display device comprises anactive-matrix-type liquid crystal display panel LPN. The liquid crystaldisplay panel LPN comprises an array substrate AR which is a firstsubstrate, a counter-substrate CT which is a second substrate disposedto be opposed to the array substrate AR, and a liquid crystal layer LQheld between the array substrate AR and the counter-substrate CT. Theliquid crystal display panel LPN includes an active area ACT where animage is displayed. The active area ACT corresponds to a region wherethe liquid crystal layer LQ is held between the array substrate AR andthe counter-substrate CT, is formed in a rectangular shape, for example,and is composed of a plurality of pixels PX arrayed in a matrix.

The array substrate AR comprises gate lines G (G1 to Gn), source lines S(S1 to Sm), switching elements SW, pixel electrodes PE, commonelectrodes CE, etc., in the active area ACT. Each of the gate lines G(G1 to Gn) is substantially extended along a first direction X andarranged in a second direction Y intersecting the first direction X.Each of the source lines S (S1 to Sm) is substantially extended alongthe second direction Y and arranged in the first direction X. The gatelines G and the source lines S may be bent in accordance with a pixellayout or a pixel shape as explained below. The switching element SW iselectrically connected to the gate line G and the source line S in eachpixel PX. The pixel electrode PE is electrically connected to theswitching element SW in each pixel PX. The common electrode CE is formedcommonly for a plurality of pixels PX and is opposed to each pixelelectrode PE, in the active area ACT. A storage capacitor CS is formed,for example, between the common electrode CE and the pixel electrode PE.

Each of the gate lines G is led to the outside of the active area ACTand is connected to a first driving circuit GD. Each of the source linesS is led to the outside of the active area ACT and is connected to asecond driving circuit SD. For example, at least parts of the firstdriving circuit GD and second driving circuit SD are formed on the arraysubstrate AR, and are connected with a driving IC chip 2. The driving ICchip 2 incorporates a controller which controls the first drivingcircuit GD and the second driving circuit SD, and functions as a signalsupply source which supplies signals necessary for driving the liquidcrystal display panel LPN. In the example illustrated, the driving ICchip 2 is mounted on the array substrate AR, outside the active areaACT. The common electrode CE is led to the outside of the active areaACT and is connected to a power supply module VS. The power supplymodule VS supplies a common potential to the common electrode CE.

FIG. 2 is a schematic plan view showing a first configuration example ofthe pixels in the array substrate AR shown in FIG. 1 as seen from thecounter-substrate side. A pixel structure to which a lateral electricmode is applied is exemplified here, and main portions necessary forexplanations alone are illustrated in the figure.

The array substrate AR comprises the gate lines G1 and G2, the sourcelines S1 to S4, the switching elements SW1 to SW6, the common electrodeCE, the pixel electrodes PE1 to PE6, a first alignment film AL1, etc.

Each of the gate lines G1 and G2 is extended linearly along the firstdirection X. Each of the source lines S1 to S4 is substantially extendedalong the second direction Y and intersects the gate lines G1 and G2. Apitch PT1 between the source line S1 and the source line S2 issubstantially equal to a pitch PT2 between the source line S2 and thesource line S3. A pitch PT3 between the source line S3 and the sourceline S4 is longer than pitch PT1 and pitch PT2.

The pixels PX1 to PX3 arranged in the first direction X are color pixelsof different colors, and the pixels PX4 to PX6 are also color pixels ofdifferent colors. The pixels PX1 and PX4 arranged in the seconddirection Y are pixels of the same color and, for example, red (R)pixels. The pixels PX2 and PX5 arranged in the second direction Y arepixels of the same color and, for example, green (G) pixels. The pixelsPX3 and PX6 arranged in the second direction Y are pixels of differentcolors and, for example, the pixel PX3 is a blue (B) pixel and the pixelPX6 is a white (W) pixel. The pixels PX1 and PX4 are located between thesource line S1 and the source line S2. The pixels PX2 and PX5 arelocated between the source line S2 and the source line S3. The pixelsPX3 and PX6 are located between the source line S3 and the source lineS4.

The pixels PX1 to PX3 are extended in a first extending direction D1that intersects the second direction Y clockwise at an acute angle. Eachof the source lines S1 to S4 located on both sides of the pixels PX1 toPX3 is extended in the first extending direction D1. The pixels PX4 toPX6 are extended in a second extending direction D2 that intersects thesecond direction Y counterclockwise at an acute angle. Each of thesource lines S1 to S4 located on both sides of the pixels PX4 to PX6 isextended in the second extending direction D2. An angle θ1 made by thesecond direction Y and the first extending direction D1 is substantiallythe same as an angle θ2 made by the second direction Y and the secondextending direction D2.

The common electrode CE is extended over a substantially entire regionof the array substrate AR and is formed commonly to the pixels PX1 toPX6. In other words, the common electrode CE is extended in the seconddirection Y over the gate lines G1 and G2, extended in the firstdirection X over the source lines S1 to S4, and disposed in each of thepixels PX1 to PX6. It should be noted that in the common electrode CE,an opening portion for making an electric connection between the pixelelectrode and the switching element is formed in each of the pixels PX1to PX6.

The Pixel PX1 comprises the switching element SW1 and the pixelelectrode PE1. The switching element SW1 is electrically connected withthe gate line G1 and the source line S1. The pixel electrode PE1 islocated between the source line S1 and the source line S2, and iselectrically connected with the switching element SW1.

The pixel PX2 comprises the switching element SW2 and the pixelelectrode PE2. The switching element SW2 is electrically connected withthe gate line G1 and the source line S2. The pixel electrode PE2 islocated between the source line S2 and the source line S3, and isadjacent to the pixel electrode PE1. In addition, the pixel electrodePE2 is electrically connected with the switching element SW2.

The Pixel PX3 comprises the switching element SW3 and the pixelelectrode PE3. The switching element SW3 is electrically connected withthe gate line G1 and the source line S3. The pixel electrode PE3 islocated between the source line S3 and the source line S4, and isadjacent to the pixel electrode PE2. In addition, the pixel electrodePE3 is electrically connected with the switching element SW3.

Similarly, the pixel PX4 comprises the switching element SW4electrically connected with the gate line G2 and the source line S1, andthe pixel electrode PE4 electrically connected with the switchingelement SW4. The pixel PX5 comprises the switching element SW5electrically connected with the gate line G2 and the source line S2, andthe pixel electrode PE5 electrically connected with the switchingelement SW5. The pixel PX6 comprises the switching element SW6electrically connected with the gate line G2 and the source line S3, andthe pixel electrode PE6 electrically connected with the switchingelement SW6.

Each of the switching elements SW1 to SW6 is, for example, a thin-filmtransistor (TFT).

Each of the pixel electrodes PE1 to PE6 is opposed to the commonelectrode CE.

Each of the pixel electrodes PE1 to PE3 is formed in an island shapecorresponding to the pixel shape extending in the first extendingdirection D1. The pixel electrode PE1 comprises a contact portion CT1electrically connected with the switching element SW1 and at least onestrip electrode PA1 extending from the contact portion CT1. The pixelelectrode PE2 comprises a contact portion CT2 electrically connectedwith the switching element SW2 and at least one strip electrode PA2extending from the contact portion CT2. The pixel electrode PE3comprises a contact portion CT3 electrically connected with theswitching element SW3 and at least one strip electrode PA3 extendingfrom the contact portion CT3.

The contact portion CT2 is arranged with the contact portion CT1 on thesame straight line along the first direction X. The contact portion CT3is located at a position displaced from the same straight line of thecontact portion CT1. The contact portion CT3 is located on a side closerto gate line G2 than the contact portion CT1 and the contact portionCT2. In the example illustrated, the contact portion CT3 is located on aside opposite to the contact portion CT1 and the contact portion CT2with gate line G1 disposed therebetween.

Each of the strip electrodes PA1 to PA3 is extended in the firstextending direction D1. In other words, the strip electrode PA1 isextended from the contact portion CT1 toward a side apart from the gateline G2. Similarly, the strip electrode PA2 is extended from the contactportion CT2 toward a side apart from the gate line G2. The stripelectrode PA2 has the same length as the strip electrode PA1. The stripelectrode PA3 is extended from the contact portion CT3 toward a sideapart from the gate line G2. The strip electrode PA3 has a lengthdifferent from the length of s the trip electrode PA1, etc., and has agreater length than the length of the strip electrode PA1 in the exampleillustrated. In other words, a full length of the pixel electrode PE3along the first extending direction D1 is greater than a full length ofeach of the pixel electrodes PE1 and PE2 along the first extendingdirection D1.

The number of strip electrodes PA1 is the same as the number of stripelectrodes PA2, and the number of strip electrodes PA3 is greater thanthe number of strip electrodes PA1. In the example illustrated, thepixel electrode PE1 comprises two strip electrodes PA1 arranged in thefirst direction X, the pixel electrode PE2 comprises two stripelectrodes PA2 arranged in the first direction X, and the pixelelectrode PE3 comprises three strip electrodes PA3 arranged in the firstdirection X.

Each of the pixel electrodes PE4 to PE6 is formed in an island shapecorresponding to the pixel shape expending in the second extendingdirection D2. The pixel electrode PE4 comprises a contact portion CT4electrically connected with the switching element SW4, and at least onestrip electrode PB1 extending from the contact portion CT4. The pixelelectrode PE5 comprises a contact portion CT5 electrically connectedwith the switching element SW5 and at least one strip electrode PB2extending from the contact portion CT5. The pixel electrode PE6comprises a contact portion CT6 electrically connected with theswitching element SW6 and at least one strip electrode PB3 extendingfrom the contact portion CT6. The contact portions CT1 to CT3 arearranged on the same straight line along the first direction X.

Each of the strip electrodes PB1 to PB3 is extended in the secondextending direction D2. In other words, the strip electrode PB1 isextended from the contact portion CT4 toward a side close to the gateline G1. Similarly, the strip electrode PB2 is extended from the contactportion CT5 toward a side close to the gate line G1. The strip electrodePB2 has the same length as the strip electrode PB1. The strip electrodePB3 is extended from the contact portion CT6 toward a side close to thegate line G1. The strip electrode PB3 has a length different from thelength of the strip electrode PB1, etc., and has a smaller length thanthe length of the strip electrode PB1 in the example illustrated. Inother words, a full length of the pixel electrode PE6 along the secondextending direction D2 is smaller than a full length of each of thepixel electrodes PE4 and PE5 along the second extending direction D2.

The number of strip electrodes PB1 is the same as the number of stripelectrodes PB2, and the number of strip electrodes PB3 is greater thanthe number of strip electrodes PB1. In the example illustrated, thepixel electrode PE4 comprises two strip electrodes PB1 arranged in thefirst direction X, the pixel electrode PE5 comprises two stripelectrodes PB2 arranged in the first direction X, and the pixelelectrode PE6 comprises three strip electrodes PB3 arranged in the firstdirection X.

The first alignment film AL1 is subjected to alignment treatment along adirection which intersects the first extending direction D1 and thesecond extending direction D2 at an acute angle less than or equal to45°. For example, an alignment direction R1 of the first alignment filmAL1 is a direction which is parallel to the second direction Y and whichintersects the first extending direction D1 or the second extendingdirection D2.

FIG. 3 is a plan view schematically showing a structural example of theswitching elements SW2 and SW3 shown in FIG. 2. In the exampleillustrated, each of the switching elements SW2 and SW3 is formed of athin-film transistor in the double-gate structure.

In other words, the switching element SW2 comprises a semiconductorlayer SC2 and a relay electrode RE2. The semiconductor layer SC2 isformed in a U-letter shape and intersects the gate line G1 at two parts.One of end sides of the semiconductor layer SC2 is connected to thesource line S2 through a contact hole CH11. The other end side of thesemiconductor layer SC2 is connected to the relay electrode RE2 througha contact hole CH12. The relay electrode RE2 overlaps the contactportion CT2 of the pixel electrode PE2, and is connected to the contactportion CT2 through a contact hole 13. The contact portion CT2 islocated on the same side as the strip electrodes PA2 with respect to thegate line G1.

The switching element SW3 comprises a semiconductor layer SC3 and arelay electrode RE3. The semiconductor layer SC3 is formed in a U-lettershape and intersects the gate line G1 at two parts. One of end sides ofthe semiconductor layer SC3 is connected to the source line S3 through acontact hole CH21. The other end side of the semiconductor layer SC3 isconnected to the relay electrode RE3 through a contact hole CH22. Therelay electrode RE3 overlaps the contact portion CT3 of pixel electrodePE3, and is connected to the contact portion CT3 through a contact holeCH23. The contact portion CT3 is located on a side opposite to the stripelectrodes PA3 with respect to the gate line G1.

In the example illustrated, the semiconductor layer SC3 is formed toface in a direction opposite to the semiconductor layer SC2. In otherwords, the semiconductor layer SC2 is folded on a side closer to thepixel electrode PE2 than to the gate line G1 and is connected to each ofthe source line S2 and the relay electrode RE2 on a side apart from thepixel electrode PE2 than from the gate line G1. In contrast, thesemiconductor layer SC3 is folded on a side apart from the pixelelectrode PE3 than from the gate line G1 and is connected to each of thesource line S3 and the relay electrode RE3 on a side closer to the pixelelectrode PE3 than to the gate line G1. In other words, the contactholes CH11 and CH12 are located on a side opposite to the contact holesCH21 and CH22 with respect to the gate line G1. In addition, the contacthole CH13 is also located on a side opposite to the contact hole CH23with respect to the gate line G1. Alternatively, as seen from anotherviewpoint, an imaginary straight line L linking the contact hole CH13formed at the contact portion CT2 and the contact hole CH23 formed atthe contact portion CT3 intersects the gate line G1.

It should be noted that the semiconductor layers SC2 and SC3 are formedof, for example, polycrystalline silicon (p-S1) but may be formed ofamorphous silicon (a-S1), an oxide semiconductor, or the like.

FIG. 4 is a plan view schematically showing an example of a layout ofthe pixels and color filters in the embodiments.

A unit pixel UP for implementing color display is composed of aplurality of different color pixels. The unit pixel UP is a minimum unitthat forms a color image displayed in the active area. The unit pixel UPis composed of, for example, six color pixels. The unit pixel UP iscomposed of the pixels PX1 to PX6. In the figure, each pixel isindicated by a one-dot-chained line.

As explained above, the pixels PX1 and PX4 are red pixels, the pixelsPX2 and PX5 are green pixels, the pixel PX3 is a blue pixel, and thepixel PX6 is a white pixel. In this configuration, the pixels PX1, PX2,PX4 and PX5 are substantially equal in area. The area of the pixel PX3is larger than the area of the pixel PX1, etc.

The counter-substrate CT comprises light-shielding layers BM, colorfilters CF1 to CF4, a second alignment film AL2, etc.

The light-shielding layers BM are disposed at boundaries of therespective pixels. In other words, the light-shielding layers BM arelocated above wiring portions such as the source lines, the gate lines,the switching elements, etc., shown in FIG. 2. In the example shown inFIG. 2, the contact portion CT3 (or the switching element SW3) isdisplaced from a position on the same straight line in which the contactportion CT1 (or the switching element SW1) and the contact portion CT2(or the switching element SW2) are arranged. For this reason, a portionextending in the first direction X, of the light-shielding layer BMshown in the figure, meanders in accordance with the layout of the arraysubstrate AR. The light-shielding layer BM is disposed at a boundarybetween the pixels of different colors, but may not be disposed at aboundary between the pixels of the same color.

The color filter CF1 is formed in a strip shape extending along thesecond direction Y. The color filter CF2 is adjacent to the color filterCF1 in the first direction X and is formed in a strip shape extendingalong the second direction Y. The color filter CF3 is adjacent to thecolor filter CF2 in the first direction X and is formed in an islandshape. The color filter CF4 is adjacent to the color filter CF3 in thesecond direction Y and adjacent to the color filter CF2 in the firstdirection X, and is formed in an island shape. The color filter CF3 andthe color filter CF4 are alternately disposed along the second directionY.

The color filter CF1 is disposed to correspond to the pixels PX1 andPX4. The color filter CF2 is disposed to correspond to the pixels PX2and PX5. The color filter CF3 is disposed to correspond to the pixelPX3. The color filter CF4 is disposed to correspond to the pixel PX6. Inthe example illustrated, the color filter CF1 is a red (R) color filter,the color filter CF2 is a green (G) color filter, the color filter CF3is a blue (B) color filter, and the color filter CF4 is a white (W)color filter. The color filters CF1 to CF4 have mutually adjacent endportions overlapping the light-shielding layers BM.

The second alignment film AL2 is subjected to alignment treatment alonga direction parallel to the alignment direction R1 of the firstalignment film AL1. An alignment direction R2 of the second alignmentfilm AL2 is, for example, mutually opposed to the alignment direction R1of the first alignment film AL1.

FIG. 5 is a cross-sectional view schematically showing a configurationof the liquid crystal display panel LPN including the pixels PX1 to PX6shown in FIG. 2.

The array substrate AR is formed by using a first insulating substrate10 having light transmissivity, such as a glass substrate and a resinsubstrate. The array substrate AR comprises the source lines S1 to S4,the common electrode CE, the pixel electrodes PE1 to PE6, a firstinsulating film 11, a second insulating film 12, a third insulating film13, the first alignment film AL1, etc., on a side of the firstinsulating substrate 10 which is opposed to the counter-substrate CT. Itshould be noted that the switching elements or the gate lines are notshown in the figure.

The source lines S1 to S4 are formed on the first insulating film 11 andcovered with the second insulating film 12. The gate lines are formedbetween the first insulating substrate 10 and the first insulating film11. The common electrode CE is formed on the second insulating film 12and covered with the third insulating film 13. The common electrode CEis formed of a transparent, electrically conductive material such asindium tin oxide (ITO) and indium zinc oxide (IZO).

The pixel electrodes PE1 to PE6 are formed on the third insulating film13 and opposed to the common electrode CE. In other words, the stripelectrodes PA1 to PA3 and the strip electrodes PB1 to PB3 are locatedabove the common electrode CE through the third insulating film 13. Thethird insulating film 13 corresponds to an interlayer insulating filmwhich is interposed between the common electrode CE and the pixelelectrodes PE1 to PE6. The pixel electrodes PE1 and PE4 are locatedbetween the source lines S1 and S2. The pixel electrodes PE2 and PE5 arelocated between the source lines S2 and S3. The pixel electrodes PE3 andPE6 are located between the source lines S3 and S4. The pixel electrodesPE1 to PE6 are formed of, for example, a transparent, electricallyconductive material such as ITO and IZO. The pixel electrodes PE1 to PE6are covered with the first alignment film AL1. The first alignment filmAL1 also covers the third insulating film 13. The first alignment filmAL1 is formed of a material having a horizontal alignment property anddisposed on a surface of the array substrate AR which is in contact withthe liquid crystal layer LQ.

In contrast, the counter-substrate CT is formed by using a secondinsulating substrate 20 having light transmissivity, such as a glasssubstrate and a resin substrate. The counter-substrate CT comprises thelight-shielding layers BM, the color filters CF1 to CF4, an overcoatlayer OC, the second alignment film AL2, etc. on a side of the secondinsulating substrate 20 which is opposed to the array substrate AR.

The light-shielding layers BM are formed on an inner surface of thesecond insulating substrate 20. The light-shielding layers BM arelocated above the source lines S1 to S4, respectively. Thelight-shielding layers BM are formed of a black resin material or alight-shielding metal material.

Each of the color filters CF1 to CF4 is formed on the inner surface ofthe second insulating substrate 20. The color filter CF1 is opposed tothe pixel electrodes PE1 and PE4. The color filter CF2 is opposed to thepixel electrodes PE2 and PE5. The color filter CF3 is opposed to thepixel electrode PE3. The color filter CF4 is opposed to the pixelelectrode PE6. The color filter CF1 is formed of a red-colored resinmaterial. The color filter CF2 is formed of a green-colored resinmaterial. The color filter CF3 is formed of a blue-colored resinmaterial. The color filter CF4 is formed of a white (or transparent)resin material. The color filter CF4 may not be disposed, may not be astrictly achromatic color filter, or may be a color filter of a palecolor (for example, pale yellow or pale blue). Boundaries between thecolor filters of different colors overlap the light-shielding layers BMabove the source lines S.

The overcoat layer OC covers the color filters CF1 to CF4. The overcoatlayer OC flattens unevenness of the surfaces of color filters CF1 toCF4. The overcoat layer OC is formed of a transparent resin material.The overcoat layer OC is covered with the second alignment film AL2. Thesecond alignment film AL2 is formed of a material having a horizontalalignment property and is disposed on a surface of the counter-substrateCT which is in contact with the liquid crystal layer LQ.

The array substrate AR and the counter-substrate CT as explained aboveare disposed such that the first alignment film AL1 and the secondalignment film AL2 face each other. At this time, a predetermined cellgap is formed between the array substrate AR and the counter-substrateCT by a columnar spacer formed on one of the substrates. The arraysubstrate AR and the counter-substrate CT are applied to each other by asealing member in a state in which the cell gap is formed. The liquidcrystal layer LQ is formed by a liquid crystal material containingliquid crystal molecules LM sealed between the first alignment film AL1and the second alignment film AL2.

A backlight unit BL is disposed on a back side of the liquid crystaldisplay panel LPN having such the above-described structure. Varioustypes can be applied as the backlight unit BL, but explanation of adetailed structure of the backlight unit BL is omitted here.

A first optical element OD1 including a first polarizer PL1 is disposedon an outer surface 10B of the first insulating substrate 10. A secondoptical element OD2 including a second polarizer PL2 is disposed on anouter surface 20B of the second insulating substrate 20. The firstpolarizer PL1 and the second polarizer PL2 are disposed to be, forexample, in a positional relationship of crossed-Nicol in whichpolarization axes of the respective polarizers cross each other at rightangles.

Next, the operation of the liquid crystal display device having theabove-explained configuration will be explained.

At an OFF state at which a voltage is not applied between the pixelelectrode PE and the common electrode CE to form a potential difference,no voltage is applied to the liquid crystal layer LQ. In other words, anelectric field is not formed between the pixel electrode PE and thecommon electrode CE. For this reason, the liquid crystal molecules LMincluded in the liquid crystal layer LQ are initially aligned in an X-Yplane by an alignment restriction force of the first alignment film AL1and the second alignment film AL2, as illustrated by a solid line inFIG. 2. In other words, the initial alignment direction of the liquidcrystal molecules LM is parallel to the second direction Y. At the OFFstate, part of the light from the backlight unit BL passes through thefirst polarizer PL1 and enters the liquid crystal display panel LPN. Thelight incident on the liquid crystal display panel LPN is linearlypolarized light orthogonal to, for example, a first absorption axis ofthe first polarizer PL1. The polarized state of the linearly polarizedlight is hardly varied when the light passes through the liquid crystaldisplay panel LPN at the OFF state. For this reason, most part of thelinearly polarized light passing through the liquid crystal displaypanel LPN is absorbed by the second polarizer PL2 (black display).

At an ON state at which a voltage is applied between the pixel electrodePE and the common electrode CE to form a potential difference, a voltageis applied to the liquid crystal layer LQ. In other words, a fringingfield is formed between the pixel electrode PE and the common electrodeCE. For this reason, the liquid crystal molecules LM are aligned in adirection different from a direction of the initial alignment in the X-Yplane, as illustrated by a broken line in FIG. 2. In a positive-typeliquid crystal material, for example, the liquid crystal molecules LM ofthe pixel PX3 are rotated counterclockwise to be aligned in a directionapproximately parallel to the fringing field, in the X-Y plane, and theliquid crystal molecules LM of the pixel PX6 are rotated clockwise to bealigned in a direction approximately parallel to the fringing field, inthe X-Y plane. At this time, the liquid crystal molecules LM are alignedin a direction corresponding to a magnitude of the electric field. Atthe ON state, linearly polarized light orthogonal to the firstabsorption axis of the first polarizer PL1 is made incident on theliquid crystal display panel LPN, and the polarized state is varied inaccordance with the aligned state of the liquid crystal molecules LMwhen the light passes through the liquid crystal layer LQ. For thisreason, at least part of the light passing through the liquid crystallayer LQ is transmitted through the second polarizer PL2 at the ON state(white display).

In such a structure, a normally black mode is implemented.

As explained above, if the unit pixel UP is composed of six color pixelsof two rows×three columns, each of the six color pixels is allocated toany one of a red pixel, a green pixel, a blue pixel, and a white pixel.For example, two color pixels in a column are allocated as the redpixels, and two color pixels in a column are allocated as the greenpixels. In addition, the color pixels in a column are allocated as theblue pixel and the white pixel, respectively.

In other words, in the unit pixel UP of the layout explained in theembodiments, two color pixels are allocated as the red pixels and twocolor pixels are allocated as the green pixels while one color pixel isallocated as the blue pixel and one color pixel is allocated as thewhite pixel. If each of all the six pixels has an equal area, brightnessof the blue pixel is insufficient. For this reason, the area of the bluepixel is increased and the brightness necessary for the blue pixel ismaintained by making the length of the blue pixel in the first directionX greater than the length of each of the red pixels and green pixels inthe first direction X.

In contrast, if the length of the unit pixel UP in the first direction Xis restricted in response to a demand for higher fineness, adjusting thearea of each of the color pixels by the length of each of the colorpixels along the first direction X alone is limited. For this reason,the red pixels and the green pixels need to be driven at a comparativelylow brightness to maintain optimum color balance. In addition, as thedifference in lengths of the color pixels along the first direction X isgreater, a proportion in areas of the color pixels in the unit pixel UPis varied more greatly and inconvenience of losing the color balancefurther occurs when misalignment occurs in the first direction X in thestep of bonding the array substrate AR and the counter-substrate CT.

Thus, according to the embodiments, the contact portion of one pixelelectrode, of three pixel electrodes arranged in the first direction X,is disposed at a position displaced from the same straight line ofcontact portions of two other pixel electrodes. For example, in the bluepixel, the pixel electrode and the switching element are electricallyconnected at positions displaced from the same straight line of the redpixels and green pixels. At this time, the pixel electrode of the bluepixel protrudes toward the white pixel side, and the contact portion ofthe pixel electrode is close to the pixel electrode of the white pixel.Thus, the area of the blue pixel contributing to the display can beexpanded in the columnar direction (or second direction Y). For thisreason, the brightness of the blue pixel can be enhanced. An optimumcolor balance can be thereby obtained with higher brightness, in theunit pixel UP. In addition, since the difference in lengths of the colorpixels in the first direction X does not become great, variation incolor balance corresponding to the misalignment in bonding the arraysubstrate AR and the counter-substrate CT can be suppressed. Displayquality can be therefore enhanced.

Furthermore, in the unit pixel UP, the area of each color pixel can beadjusted in accordance with the length of the first direction X andlength of the second direction Y, and the degree of freedom in thelayout can be improved.

In the above-described embodiments, the shape-modified layout in whichthe pitches of the red pixels and the green pixels are equal to eachother and the pitches of the blue pixel and the white pixel are greaterthan the pitches of the red pixels and the green pixels has beenexplained, but, in the shape-modified layout, the color pixels may becombined in a different manner from that mentioned above and all thepitches of the red pixels, green pixels, blue pixel and white pixel maybe different from each other. The pixel electrode disposed in each ofthe color pixels needs only to comprise an arbitrary number of stripelectrodes that is set in accordance with each pixel pitch, and is notlimited to the above-explained example.

Next, another configuration example will be explained.

FIG. 6 is a schematic plan view showing a second configuration exampleof the pixels in the array substrate AR shown in FIG. 1 as seen from thecounter-substrate side.

The second configuration example is different from the firstconfiguration example shown in FIG. 2 with respect to a feature thatgate line G1 is bent in part. The other constituent features are thesame as those in the first configuration example, and explanations areomitted.

In the example illustrated, similarly to the first configurationexample, the contact portions CT1 and CT2 are arranged on the samestraight line along the first direction X while the contact portion CT3is disposed at a position displaced from the same straight line of thecontact portion CT1, and the pixel electrode PE3 is expanded toward thepixel electrode PE6 along the second direction Y.

The gate line G1 is extended linearly along the first direction X inaccordance with the contact portions CT1 and CT2, and bent to a sideapart from the strip electrodes PA3 in accordance with the contactportion CT3 or a side close to the pixel electrode PE6. In other words,the contact portion CT3 is located on the same side as the stripelectrodes PA3 with respect to the gate line G1, in the pixel electrodePE3. In addition, the contact portion CT3 is located on the same side asthe contact portions CT1 and CT2 with respect to the gate line G1. Thegate line G1 is electrically connected with each of the switchingelements SW1 to SW3. The switching elements SW1 to SW3 are electricallyconnected with the pixel electrodes PE1 to PE3, respectively.

In the second configuration example, too, the area contributing todisplay of pixel PX3 can be increased in the second direction Y, and thesame advantage as the first configuration example can be obtained. Inaddition, in the second configuration example, the switching elementsSW1 to SW3 can be connected with the pixel electrodes PE1 to PE3, in thesame direction, even in a layout in which the contact portions CT1 toCT3 are not located in the same straight line. In other words, theswitching element SW3 has a structure different from the switchingelement SW2, etc., in the first configuration example, as shown in FIG.3, while the switching elements SW1 to SW3 can be formed in the samestructure irrespective of the positions of the respective contactportions CT1 to CT3, in the second configuration example.

FIG. 7 is a schematic plan view showing a third configuration example ofthe pixels in the array substrate AR shown in FIG. 1 as seen from thecounter-substrate side.

The third configuration example shown in the figure is different fromthe first configuration example shown in FIG. 2 with respect to featuresthat the contact portions CT1 to CT3 are arranged in the same straightlight along the first direction X and the strip electrodes PA3 areformed to be longer than the strip electrodes PA1 and PA2, and that thecontact portion CT6 is disposed at a position displaced from the samestraight line of the contact portions CT4 and CT5.

In the example illustrated, the contact portions CT4 and CT5 arearranged in the same straight line along the first direction X while thecontact portion CT6 is disposed at a position displaced from the samestraight line of the contact portions CT4 and CT5, and the pixelelectrode PE6 is eccentrically disposed toward the pixel electrode PE3along the second direction Y. The strip electrodes PB1 and PB2 have anequal length while the strip electrode PB3 has a shorter length than thestrip electrode PB1.

The gate line G2 is extended linearly along the first direction X inaccordance with the contact portions CT4 and CT5, and bent to the pixelelectrode PE3 side in accordance with the contact portion CT6. The gateline G2 is electrically connected with each of the switching elementsSW4 to SW6. The switching elements SW4 to SW6 are electrically connectedwith the pixel electrodes PE4 to PE6, respectively.

The gate line G1 is extended linearly along the first direction X inaccordance with the contact portions CT1 to CT3. The gate line G1 iselectrically connected with each of the switching elements SW1 to SW3.The switching elements SW1 to SW3 are electrically connected with thepixel electrodes PE1 to PE3, respectively.

The unit pixels UP shown in the figure are repeatedly disposed in thesecond direction Y. In other words, tip portions of strip electrodes PA3are extended toward the bent portion of the gate line G2.

In the third configuration example, too, the area contributing todisplay of pixel PX3 can be increased in the second direction Y, and thesame advantage as the first configuration example can be obtained.

According to the embodiments, as described above, the liquid crystaldisplay device capable of enhancing the display quality can be provided.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A liquid crystal display device comprising: afirst substrate comprising first to third switching elements, a firstpixel electrode which comprises a first contact portion electricallyconnected with the first switching element and a first strip electrodeextended from the first contact portion with a first length, a secondpixel electrode which comprises a second contact portion electricallyconnected with the second switching element and located on a samestraight line with the first contact portion and a second stripelectrode extended from the second contact portion with a second lengthequal to the first length, and a third pixel electrode which comprises athird contact portion electrically connected with the third switchingelement and disposed at a position displaced from the same straight lineof the first contact portion and a third strip electrode extended fromthe third contact portion with a third length different from the firstlength; a second substrate comprising a first color filter opposed tothe first pixel electrode, a second color filter opposed to the secondpixel electrode, and a third color filter opposed to the third pixelelectrode; and a liquid crystal layer held between the first substrateand the second substrate.
 2. The device of claim 1, wherein the thirdlength is greater than the first length.
 3. The device of claim 2,wherein the third color filter is a blue color filter.
 4. The device ofclaim 1, wherein the third length is smaller than the first length. 5.The device of claim 4, wherein the third color filter is a white colorfilter.
 6. The device of claim 1, wherein the first substrate furthercomprises a gate line electrically connected with the first to thirdswitching elements, and the third contact portion is located on a sideopposed to the first and second contact portions with respect to thegate line.
 7. The device of claim 1, wherein the first pixel electrodecomprises m first strip electrodes, the second pixel electrode comprisesm second strip electrodes, and the third pixel electrode comprises nthird strip electrodes, and m and n are integers greater than or equalto 1 and n is greater than m.
 8. The device of claim 1, wherein thefirst substrate further comprises a fourth switching element, and afourth pixel electrode which comprises a fourth contact portionelectrically connected with the fourth switching element and a fourthstrip electrode extended from the fourth contact portion with a fourthlength different from the first to third lengths, and the secondsubstrate further comprises a fourth color filter opposed to the fourthpixel electrode.
 9. The device of claim 8, wherein the fourth length issmaller than the third length.
 10. The device of claim 9, wherein thethird color filter is a blue color filter and the fourth color filter isa white color filter.
 11. The device of claim 1, wherein the firstsubstrate further comprises a common electrode opposed to the first tothird pixel electrodes.
 12. The device of claim 1, wherein the firstsubstrate further comprises a gate line, and first to fourth sourcelines intersecting the gate line, the first switching element iselectrically connected with the gate line and the first source line, thesecond switching element is electrically connected with the gate lineand the second source line, and the third switching element iselectrically connected with the gate line and the third source line, anda first pitch between the first source line and the second source lineis equal to a second pitch between the second source line and the thirdsource line, and a third pitch between the third source line and thefourth source line is greater than the first pitch.
 13. The device ofclaim 12, wherein the gate line is extended linearly along a direction.14. The device of claim 12, wherein the gate line is extended linearlyin accordance with the first contact portion and the second contactportion and bent in accordance with the third contact portion.
 15. Thedevice of claim 8, wherein the fourth pixel electrode is eccentricallydisposed toward the third pixel electrode.
 16. The device of claim 8,wherein the first substrate further comprises a first gate line and asecond gate line arranged parallel to the first gate line in a seconddirection, and the first gate line is extended linearly along the firstto third contact portions, and the second gate line is bent inaccordance with the fourth contact portion.
 17. The device of claim 1,wherein each of the first to third switching elements comprises asemiconductor layer and a relay electrode.
 18. The device of claim 17,wherein the relay electrode overlaps the first contact portion and iselectrically connected to the first contact portion through a contacthole formed in the first contact portion.
 19. The device of claim 8,wherein each of the first to fourth switching elements comprises asemiconductor layer and a relay electrode.
 20. The device of claim 19,wherein the relay electrode overlaps the first contact portion and iselectrically connected to the first contact portion through a contacthole formed in the first contact portion.